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std:: swap (std::unordered_multimap)

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std::unordered_multimap
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std::swap (std::unordered_multimap)
(C++20)
Deduction guides (C++17)
定义于头文件 <unordered_map>
template < class Key, class T, class Hash, class KeyEqual, class Alloc >

void swap ( std:: unordered_multimap < Key, T, Hash, KeyEqual, Alloc > & lhs,

std:: unordered_multimap < Key, T, Hash, KeyEqual, Alloc > & rhs ) ;
(C++11 起)
(C++17 前)
template < class Key, class T, class Hash, class KeyEqual, class Alloc >

void swap ( std:: unordered_multimap < Key, T, Hash, KeyEqual, Alloc > & lhs,
std:: unordered_multimap < Key, T, Hash, KeyEqual, Alloc > & rhs )

noexcept ( /* 见下文 */ ) ;
(C++17 起)
(C++26 起为 constexpr)

为 std::swap 算法针对 std::unordered_multimap 进行特化。交换 lhs 与 rhs 的内容。实际调用 lhs. swap ( rhs ) 。

目录

参数

lhs, rhs - 待交换内容的容器

复杂度

常量。

异常处理

noexcept 规范：
noexcept ( noexcept ( lhs. swap ( rhs ) ) )
(C++17 起)

示例

运行此代码 
#include <algorithm>
#include <iostream>
#include <unordered_map>
int main()
{
    std::unordered_multimap<int, char> alice{{1, 'a'}, {2, 'b'}, {3, 'c'}};
    std::unordered_multimap<int, char> bob{{7, 'Z'}, {8, 'Y'}, {9, 'X'}, {10, 'W'}};
    auto print = [](std::pair<const int, char>& n)
    {
        std::cout << ' ' << n.first << ':' << n.second;
    };
    // 交换前打印状态
    std::cout << "Alice:";
    std::for_each(alice.begin(), alice.end(), print);
    std::cout << "\nBobby:";
    std::for_each(bob.begin(), bob.end(), print);
    std::cout << '\n';
    std::cout << "-- SWAP\n";
    std::swap(alice, bob);
    // 交换后打印状态
    std::cout << "Alice:";
    std::for_each(alice.begin(), alice.end(), print);
    std::cout << "\nBobby:";
    std::for_each(bob.begin(), bob.end(), print);
    std::cout << '\n';
}

可能的输出： 

Alice: 1:a 2:b 3:c
Bobby: 7:Z 8:Y 9:X 10:W
-- SWAP
Alice: 7:Z 8:Y 9:X 10:W
Bobby: 1:a 2:b 3:c

参见

交换内容
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